Due to the "Great Leap Forward", China suffered in the largest famine in human history in 1959-1961 and caused 30 million people starved to death--about to cover the number of births. It made an anomaly in the demographic model that to have a sudden increase in death rate in stage 2 with a shaping decrease in population within the nation.
Under the ridiculous ideas of Mao, industrial productions had to be increased by all means and thus all citizens including farmers, had to involve into the industrial sector. Therefore, there was little attention paid in farming or other agricultural areas. All cooking equipments were collected and to be malted into steel. Famine began to spread across the country.
People were not allowed to cook in their own kitchens and who ever broke the regulation would be beaten to death. The only allowed-smoke came from the appointed house once of two days.
The family cooked the food for the entire village by mixing sweet potato and leaves. People were then queuing up for food outside the house. Elderly, women and children were the weakest in the line. They would be pushed on the floor and never got up. The ones who able to finish the food didn't mean to survive since sometimes the leaves got solidified in the stomach and the men died.
Due to the pressure from the commune leaders, the officials refused to report the truth of policy error, instead, to tell what the leaders wanted to hear. This further worsened the situation.
Besides, the state-promoted "close-planting" made the soil became thin. Farmers had been told to plant crops closest to each other in order to maximize the productivity. Nonetheless, it won't work as they would compete and extract all the nutrients and thus the soil...